Preparation of 2, 2, 3-trichlorohepta-fluorobutane



PREPARATION OF 2,2,3-TRICHLOROHEPTA- FLUOROBUTANE Charles F. 'Baranauckas and William E. Ashton, Niagara Falls, N.Y., assignors to Hooker ChemicalCorporation,

New York, N.Y., a corporation of New York No Drawing. Original application August 13, 1956, Se-

rial No. 603,826, now Patent No. 2,862,036, dated November 25, 1958. Divided andthis application August 26, 1958, Serial No. 759,114

1 Claim. (Cl. 260-6535) The compound 2,2,3-trichloroheptafluorobutane prepared by the process of this invention is useful as a solvent in, a variety of reactions. Further, the compound is useful as a heat transfer agent due to its chemical inertness, its boiling point and other physical properties.

In United States Patent 2,436,357 Gochenour et al. described the fluorination of hexachlorobutadiene in such manner as to eliminate one of the double bonds, and cause the shift of the other double bond to the C -C carbon atoms while substituting fluorine atoms for some of the chlorine atoms present in the original molecule, thereby to form dichlorohexafiuorobutene-Z, and monochloroheptafluorobutene-2. The fluorinating agent employed according to Gochenour et al. is a composition containing an antimony halide, hydrogen fluoride, and elemental chlorine.

We have now found that when starting with a perhalocarbon represented by the formula CXCX'CX'CX in which X consists of two or three atoms of fluorine, chlorine or a mixture thereof and X consists of one or two atoms of chlorine, in admixture with a fluorinating agent containing an antimony halide, hydrogen fluoride, and elemental chlorine and While maintaining the temperature of the reaction zone between about 200 degrees and about 300 degrees centigrade for a contact time of 'less than ten hours, 2,2,3-trichloroheptailuorobutane may be prepared in goodyield.

The reactions illustrated in the following equations show the preparation of the desired compound 2,2,3-trichloroheptafluorobutane by reacting astraight chain perhalocarbon containing four carbon atoms, for example, a

butadiene, such as hexachlorobutadiene; a butene, such as 2,3-dichlorohexafluorobutene-Z and a butane, such as 2,2,3,3-tetrachlorohexabutane 'with a fluorinating agent containing an antimony halide, hydrogen fluoride and elemental chloride.

1 Sb ClzFE-X H hlo obutadiene em I org-c c1.o OlF-CFa+7HC1 2 3-di h1 ohexafluorobutene-2 c or CF -CGh-OClF-CFHHCI 2,2,3-trich1oroheptafluorobutane 2,2,3-trichloroheptafluorobutane wherein X has a value of 0 to 5 inclusive.

Other starting materials including l,2,3 -tr'-ichloropentafluorobutene 2; 1,l,2,3 tetrachlorotetrafluorobutene 2; 1,1, 1,2,3 pentachlorotrifluorobutene 2; 1,1,2,3,4,4-11exachlorodifluorobutene 2 and '1,1,1,'2,3,4,4,4 octachlorobutene-2 which forms 2,3-dichlorohexafluorobutene-2 in situ under the conditions of the process of this invention, may be used.

The following examples illustrate various ways of practising our invention, but it is to be understood that the specific details given in the examples have been chosen for the purpose of illustration and are not intended to limit our invention, except as defined in the appended claims. In theexamples, all parts "are expressed by weight except where otherwise defined.

Example 1 A Monel-clad autoclave that had been pre-cooled to about minus 50 degrees centigrade in the absence of moisture was charged with 1,398 parts of 2,3-dichlorohexafluorobutene-Z, 1.074 parts of antimony trifluoride, and 852 parts of chlorine and was sealed. The autoclave was then inserted into a rocking type heating jacket and the temperature was recorded automatically from a thermocouple inserted in the thermowall of the autoclave.

The reactor was heated rapidly to a temperature of about 250 degrees centigrade, and maintained at this temperature for seven hours and attained a pressure of approximately 1200 p.s.i.g. Thereafter the reactor was cooled rapidly tobelow zero and the contents vented into a collection system consisting of a series of caustic traps to neutralize the acidic components then into a Dry-Ice trap to collect any low boiling products. After the initial venting had subsided, the reactor was heated to degrees centigrade to distill over the higher boiling products to the collection system. The antimony salts remaining in the reactor were cooled to room temperature and were decomposed by the addition of 1,000 milliliters of hydrochloric acid. The decomposed salt slurry was extracted with carbon tetrachloride to insure complete recovery of the organic products. The crude product Was Washed, dried and fractionated. The desired product, 2,2,3-trichloroheptafluorobutane (82.7% yield) was collected over a temperature range of 96 degrees to 98 degrees centigrade and then was treated with moist soda ash to remove any acidic materials to provide a clear water-like liquid having a refractive index of 1.3525 :t0.0002 at 20 degrees centigrade.

Example 2 In an apparatus similar to that described in connection with Example 1, 1,398 parts of 2,3-dichlorohexafluorobutene-2, 1,800 parts of antimony pentachloride, 300 parts of chlorine and 600 parts of hydrogen fluoride were charged into the Monel clad autoclave.

The reactor contents were heated rapidly to a temperature of 250 degrees centigrade and maintained at this temperature for seven hours. The product, 868 parts of 2,2,3-trichloroheptafluorobutane (80.5% yield) was obtained in a manner after that described in Example 1.

Example 3 In an apparatus and under conditions similar to that described in connection with Example 1, 261 parts of hexachlorobutadiene, 1200 parts of antimony pentachlo- 3 ride, 600 parts of hydrogen fluoride and 200 parts of chlorine were charged into the autoclave.

The reactor contents were heated rapidly to a temperature of 250 degrees centigrade and maintained at this to form desired product may be incomplete thereby entailing high cost of recovering and recycling unreacted material to subsequent operation. Accordingly, the time of contact is determined by balancing the economic adtemperature for four hours. The product, 133 parts of 5 vantage of high reactor throughput obtained at short 2,2,3-tr1chloroheptafluorobutane (46.2% yield) was obcontact times against the cost of recovery of unreacted tained in a manner after that described in Example 1. starting material. It has been found that to obtain opti- Example 4 mum conditions, passage of the starting material in con- 5 tact with the fiuorinating agent should be controlled to In f h h f cohdltlohs slh'lllal' to that effect a residence or contact time of less than ten hours described in connectlon with Example 1, 517 parts of l h h i d of f l h i h hours are 2,2,3,3-tetrachlorohexafluorobutane, 600 parts of antif r L molly pentachlol'lde and 600 Parts of hydrogen flhol'lde Agitation is desirable in the process of this invention were chargedmto the autoclave especially since the reactants are not mutually soluble The reactor cmtents w heated raPldly to atempera' in one another. The reaction slows down appreciably ture of 250 degrees eehtlgtade five hours- The P without agitation of the liquid. Agitation may be accomf 180 Parts P 21?,3'tnchloroheptafluorobutane plished by mechanical means such as by mechanical y Was Ohtahled 111 a manner after that described In stirrers and pulsating or rocking autoclaves. The flu- Example orinating agent contains an antimony halide and hydro- Example 5 gen fluoride and/or elemental chlorine depending upon O hl b q (0 99 m01e, 329 grams) and antithe starting material as shown in the above equations. mony trifluoride (3 moles, 536 grams) were placed in a The Preferred antimony halides a the antimony ch10- Monel autoclave with a capacity of three liters. The autorefluol'ides Such as ahtimohy dlehlomtlifluel'ide- These clave and contents were gradually heated with agitation halides may he P p by reacting antlthohy P over a -hour period to approximately 200 degrees centi- 25 chloride with hydrogen fluoride h temheratures abPut grade and maintained at this temperature for an addidegfeee Centigrade by l'eaetlhg f y fluorides tional five hours. The bomb and contents were cooled Wlth ehloflhe at about 100 degrees eehtlgfade- The to 50 degrees centigrade and the pressure within the auto- Process of this ihyehtioh y he conducted hatehwlse clave was released by venting it into a receiver cooled in cotltihuehsly- The Tea-(1101115 Preferably conducted under a b f Dry Ice and ethanol. Aft cooling the bomb the vapor pressure of the reactants at the temperature and contents to below 20 degrees centigrade, the material p y which keeps the 'l'eaetahts tt y 111 the remaining in the bomb was wash d four ti ith 6 N liquid phase and increases the mutual solubility thereof. hydrochloric acid, once with water, once with dilute While We have indicatedthataptlmpny fhchlorotnfluonde aqueous sodium carbonate, and combined with the mateis the Preferred antimony hahde, 1t W be ppa e to rial collected in the receiver. After drying, this material those Skilled in the art that the Pt cempesltlohef was rectified. 2,3-dichlorohexafluorobutene-Z was obthe antim y halide y y dllrlhg the Course of the tained in 5 7 percent yield. reaction- The following table contains the results of examples of .It is to be understood that the above described examples the process of this invention wherein reaction conditions are simply illustrative of the application of the principles were varied. of the invention. Numerous other modifications may be TABLE Example 0 01455, Sb01 SbFg, HF, 01, Temp., Press., Reaction C4OI F Residual, Yield No. pts. pts. pts. pts. pts. C. p.s.i.g. time, pts. pts. 0401 13 hrs. Percent It is critical that the temperature range in the process readily devised by those skilled in the art which will cmof this invention be between about 200 degrees and about body the principles of the invention and fall within the 300 degrees centigrade, although the preferred temperaspirit and scope thereof. ture range is between about 225'degrees and about 275 We claim: 5 degrees centigrade. At temperatures above 275 degrees A process for making 2,2,3-trichloroheptafluorobutane Centigrade, the amount of 2,3-dichlorooctafluorobutane which includes: heating 2,2,3,3-tetrachlorohexafluorobuproduced becomes appreciable and results in a decreased tane with a fluorinating agent containing an antimony yield of the desired product. At temperatures below halide and hydrogen fluoride while maintaining the reabout 225 degrees centigrade, the yield of product drops action temperature between about 200 degrees and 300 oif sharply and most of the starting material isrecovered degrees centigrade for a contact time of less than ten as 2,2,3,3-tetrachlorohexafluorobutane, which may be rehours. cycled to produce the desired product.

The contact time of the starting material with the References Clted m the file of this Patent fluorinating agent may be varied to some extent without UNITED TES T T noticeable sacrifice of advantageous high efiiciency of 2 005 703 Daudt etal J 13, 9 5 operation. However, if contact time is excessive, the 2 005 710 Daudt et 1 June 13 1935 capacity of the reactor is low thereby causing economic disadvantages in the operation. On the other hand, if FOREIGN PATENTS Great Britain "Nov. 9, 1955 contact time is too short, the reaction of starting material 

